In rock drilling and rock bolting, one often uses a rock drilling rig where one or more drilling machines are borne by respective movable arms, or booms.
Depending on the type of drilling, such as tunneling or ore mining, different types of rock drilling rigs are used. For example, when driving a tunnel, one often uses large machines with a plurality of booms, so as to drill a plurality of holes at the same time, or nearly so, and to reach across the entire, usually broad cross sectional surface that the tunnel requires from a single supporting position.
In ore mining, on the other hand, it is often desirable for economic reasons to mine the ore in such a way that only the ore body is mined, thereby reducing as much as possible the amount of excess rock that needs to be handled. This means that, when mining small ore bodies and/or when only a small portion of the ore body contains the desired ore, the mining can occur at very low gallery heights, with corresponding requirements for the rock drilling rig.
Thus, different situations place different requirements on the rock drilling rig, and therefore rock drilling rigs occur in many different designs, and hence also with many different types of booms.
A boom usually consists of an elongated structure, whose one end is normally secured to a supporting element, such as a vehicle, by one or more links. Moreover, a drilling machine is usually hinged to the end of the boom away from the support via one or more additional links.
However, the drilling machine is usually not attached directly to the boom, but instead is normally displaceable attached to the boom via a feeding arrangement consisting of a feed holder, which carries a feed beam arranged displaceable relative the feed holder, and furthermore the drilling machine can usually move relative to the feed beam so as to achieve good freedom of adjustment during drilling without the need for the supporting element to have to move.
Even though booms of the above type work well in many applications, it can be difficult to create a boom that simultaneously fulfils both needs and/or requirements on rig mobility and maneuverability when drilling in a desired manner, especially for rock drilling rigs designed for very narrow galleries. Therefore, there is a need for an improved boom for use particularly with rock drilling rigs designed to work at low gallery height.